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Albert Härtl

Publications and source records attributed to Albert Härtl.

24 records · Page 2Linked to original sources
PubMed2002

Defective Hyphal induction of a Candida albicans phosphatidylinositol 3-phosphate 5-kinase null mutant on solid media does not lead to decreased virulence.

A phosphatidylinositol 3-phosphate [PI(3)P] 5-kinase gene (CaFAB1) of the most important human pathogenic yeast, Candida albicans, was cloned and sequenced. An open reading frame was detected which encodes a 2,369-amino-acid protein with a calculated molecular mass of 268 kDa and a relative isoelectric point of 6.76. This protein exhibits 38% overall amino acid sequence identity with Saccharomyces cerevisiae Fab1p. We localized the CaFAB1 gene on chromosome R. To determine the influence of the PI(3)P 5-kinase CaFab1p on processes involved in C. albicans morphogenesis and pathogenicity, we sequentially disrupted both copies of the gene. Homozygous deletion of C. albicans CaFAB1 resulted in a mutant strain which exhibited defects in morphogenesis. A Cafab1 null mutant had enlarged vacuoles, an acidification defect, and increased generation times and was unable to form hyphae on different solid media. The sensitivities to hyperosmotic and high-temperature stresses, adherence, and virulence compared to those of wild-type strain SC5314 were not affected.

Amino Acid Sequence↗
PubMed2000

A phosphatidylinositol 3-kinase of Candida albicans influences adhesion, filamentous growth and virulence.

To determine if cellular functions of the phosphatidylinositol 3-kinase CaVps34p are related to processes governing Candida albicans pathogenicity, both copies of the gene were sequentially disrupted. Homozygous deletion of C. albicans VPS34 resulted in a mutant strain which exhibited defects not only in intracellular vesicle transport processes but also in morphogenesis. The CaVPS34 null mutant was unable to form hyphae on different solid media whilst showing a significantly delayed yeast-to-hyphae transition in liquid media. In addition, the mutant was rendered hypersensitive to temperature and osmotic stresses and had a strongly decreased ability to adhere to mouse fibroblast cells compared to the wild-type strain SC5314. Finally, evidence was obtained that CaVPS34 is essential for pathogenicity of C. albicans as the CaVPS34 null mutant was shown to be avirulent in a mouse model of systemic infection. C. albicans pathogenicity was restored to a near wild-type degree upon reintroduction of CaVPS34 into the chromosome of the null mutant, demonstrating that the observed avirulence corresponded to the loss of CaVPS34. Thus, the results suggest that CaVPS34 may serve as a potential target for antifungal drugs.

Animals↗
PubMed1999

A multicopper oxidase gene from Candida albicans: cloning, characterization and disruption.

A multicopper oxidase gene from the human pathogenic yeast Candida albicans was isolated and characterized. An open reading frame of 1872 bp, designated CaFET3, was identified, encoding a predicted protein of 624 amino acids and a molecular mass of 70.5 kDa. The identity between the deduced amino acid sequences of CaFET3 and the Saccharomyces cerevisiae FET3 gene is 55%. CaFET3 was localized on chromosome 6. A null mutant (fet3delta/fet3delta) was constructed by sequential gene disruption. Unlike the C. albicans SC5314 wild-type strain the fet3delta mutant was unable to grow in low-iron medium. The lack of growth of a S. cerevisiae fet3delta mutant in iron-limited medium was compensated by transformation with CaFET3. The null mutant strain showed no change in pathogenicity compared with the wild-type strain in the mouse model of systemic candidiasis.

Amino Acid Sequence↗
PubMedDate not supplied

Isolation, structure elucidation and biological activities of trichofumins A, B, C and D, new 11 and 13mer peptaibols from Trichoderma sp. HKI 0276W.

Trichofumins A-D were isolated from cultures of Trichoderma sp. HKI 0276 as new 11 and 13mer peptaibols. Similar to 15mer peptaibols they promote morphogenesis of the fungus Phoma destructiva and cause hypothermia in mice as a characteristic of neuroleptic activity. Membrane measurements using a synthetic BLM model showed that A, B, C and D increased membrane permeability for cations in a similar manner as was shown for larger peptaibols but with comparably lower efficiency.

Animals↗
PubMedDate not supplied

Differences in membrane pore formation by peptaibols.

The efficiencies of membrane pore formation by 14 naturally occurring peptaibols and two structurally modified ampullosporins were compared using an artificial bilayer membrane model. Major differences were found in the dependence on peptide sequences and the constituting amino acids. Alamethicin F-30, chrysospermins C/D, paracelsin and texenomycin A displayed higher activity by several orders of magnitude in comparison with smaller peptaibols containing < 17 amino acids such as ampullosporins, trichofumins. bergofungins and cephaibols. Biological activities such as the induction of pigment formation by the fungus Phoma destructiva and long acting hypothermia and depression of locomotor activity in mice were correlated with moderate membrane permeabilization. No or weak membrane activities corresponded with biological inactivity. Highly membrane-active structures such as alamethicin F-30, chrysospermin C, texenomycin A and paracelsin A displayed antibiotic effects against the fungus and toxicity in mice.

Animals↗